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The anode potential in microbial fuel cells (MFCs) defines the possible metabolic energy gain (PMEG) for the bacteria growth. This study focused on the mechanism behind anode potential controlling microbial growth and power generation in MFCs from an energy perspective. Four sets of MFCs were operated with varied conditions: three with different applied anode potential (−160, 0, and 400 mV vs standard hydrogen electrode (SHE)) and one with an external resistor (500 Ω). A model strain Geobacter sulfurreducens was used here. The evolution of biomass was measured and its quantitative relationship with PMEG was analyzed. Linear voltammetry and cyclic voltammetry were also carried out. Results indicated a notable gain in biomass and power density when anode potential increased from −160 to 0 mV. However, no gain in biomass and power generation was detected when anode potential further …